The invention concerns an alarm clock and preferably an alarm mechanism for an autonomous radio-controlled timepiece.
It is known that the cam engaging mechanism usually found in alarm clocks for the actuation of the electromechanical switching element to activate an electroacoustic alarm signal generator involves a tolerance or play of several minutes. Such response inaccuracies are not desirable, especially in the case of an autonomous radio-controlled timepiece for the latter, the state of the display is quasi-continuously monitored and, if necessary, corrected by a radio signal, the most accurate technical time basis. If the autonomous timepiece is offered to customers as the most accurate clock of the world, there should not occur a deviation of several minutes for an alarm signal. Such a timepiece is disclosed in DE-OS 39 34 383.
An alarm actuating angular position query, is somewhat more accurate (see U.S. Pat. No. 4,209,969 for example). There, by means of a manual knob, a minute setting disk is lockingly rotated by way of a gear and, in turn, it indexes an hour setting disk forward by a single hour division. The setting disks are equipped with contact springs, which scan over contact plates rotated by the hand mechanism and which lead to the actuation of the signal generator when the wheels of the alarm clockworks occupy a predetermined actuating angular position. However, such a setting operation from the manual rotating knob through the minute switching disk to the hour switching disk requires, especially in the case of long setting distances, a time-consuming moving effort on the poorly handling rotating knob and a high installation volume for such an operational coupling and for the mutually coordinated digital representations of the instantaneous setting disk positions.
In view of these facts, it is the object of the invention to equip an alarm clock of the above-described type with an alarm signal actuating apparatus that is simple to operate, which may be built into an alarm clock inexpensively by virtue of its compact configuration, and which is suitable for installation as an accessory for a radio-controlled timepiece with a hands display because of its extremely accurate response accuracy.